This invention relates to an automotive exhaust gas recirculation (EGR) system module, and more particularly, to an EGR system having an electric vacuum regulator (EVR) valve and a differential pressure (DP) sensor combined in a single assembly.
Various systems have been developed to reduce the emission of undesirable combustion products, such as nitrogen oxides (NOX), from internal combustion engines. One such system is the EGR system. In EGR systems, a portion of the engine exhaust is recirculated into the intake manifold where it mixes with incoming air. The mixture of the exhaust gases with the air-fuel mixture in the engine cylinders provides lower peak temperatures during combustion, resulting in a reduction in the quantity of NOX produced.
Known EGR systems utilize an EGR tube to divert a portion of the exhaust gases from an engine back into the intake manifold of the engine. A vacuum-operated EGR valve is arranged between the EGR tube and the intake manifold to regulate the flow of exhaust gases into the manifold. The intake manifold provides the vacuum source for operating the EGR valve. A first hose connects the manifold to an EVR valve, and a second hose connects the EVR valve to the EGR valve. The EVR valve receives a control signal from the engine control unit (ECU) and regulates the amount of vacuum provided to the EGR valve, which in turn limits the flow of exhaust gases into the intake manifold.
The ECU computes the EVR control signal based on a measurement of the differential pressure of exhaust gases between two points in the EGR tube. The differential pressure reflects the amount of flow of exhaust gases in the system. The pressure measurement is obtained using a DP sensor. The DP sensor operates by measuring the pressure of exhaust gases at locations on either side of a flow restriction, or orifice, in the EGR tube. The DP sensor continuously determines a delta pressure value for the exhaust gases and provides corresponding electronic data to the ECU. The ECU then uses this data to compute the EVR control signal.
There are several drawbacks associated with known EGR systems. The individual sensors and actuators used in these systems each require mounting brackets, electrical connections, and input and outlet hoses. Further, the DP orifice and hose connections on the EGR tube require additional manufacturing steps during production of the tube. Finally, the components in proximity to the exhaust system must be made from special heat-resistant materials to allow them to withstand the heat produced by the exhaust gases. The additional, specialized parts and the added manufacturing and assembly steps result in high production costs.
The present invention provides a system module integrating an EGR system, an EVR valve, and a DP sensor into a single unit. This system module can be mounted directly on an intake manifold of an internal combustion engine. Moreover, a single, common port on the intake manifold can provide a vacuum input connection to the EVR and the DP sensor of the system module.
The DP sensor measures exhaust pressure differential at locations upstream and downstream of an orifice that can be formed in a gasket sealing the EGR valve to the intake manifold. The upstream measurement location is in an EGR body, and the downstream location is in the intake manifold. Both orifices are located downstream of the EGR valve.
The present invention provides a system module for recirculating exhaust gases from an internal combustion engine to an intake manifold of the internal combustion engine. The system module comprises a body including a passageway extending between an inlet and an outlet, the passageway communicating a flow of the exhaust gases; an orifice constricting the flow of the exhaust gases proximate the outlet; a valve located in the passageway between the inlet and outlet, the valve regulating the flow of the exhaust gases; and a port extending through the body and in fluid communication with the passageway, the port being aligned with the orifice along a common axis.
The present invention also provides an exhaust gas recirculation module. The module comprises a valve assembly including a body having a passageway and including a pintle controlling a flow of exhaust gases through the passageway, the exhaust gases having a pressure; a pressure sensor coupled to the valve assembly; and a pressure communication pathway providing fluid communication between the passageway and the pressure sensor, the pathway communicating the pressure of the exhaust gases to the pressure sensor.
The present invention further provides a method of determining exhaust gas pressure. The exhaust gas is recirculated from an internal combustion engine to an intake manifold of the internal combustion engine. The method comprises providing a body including a passageway extending between an inlet and an outlet, the passageway communicating a flow of the exhaust gases; providing an orifice constricting the flow of the exhaust gases proximate the outlet; integrally mounting an exhaust gas pressure sensor on the body; and aligning a port along a common axis with the orifice, the port extending through the body and providing fluid communication between the passageway and the exhaust gas pressure sensor.